Cobalt phthalocyanine-based molecular materials for the electrocatalysis and electroanalysis of 2-mercaptoethanol, 2-mercaptoethanesulfonic acid, reduced glutathione and L-cysteine

We have investigated the electrocatalytic activity of cobalt tetra-aminophthalocyanine (CoTAPc) for the one-electron oxidation of thiols of various sizes, namely 2-mercaptoethanol, 2-mercaptoethanesulfonic acid, reduced glutathione and L-cysteine, using adsorbed monomeric CoTAPc and electropolymerized poly-CoTAPc films of different thickness on a vitreous carbon electrode. Our results show. that the electrocatalytic activity of poly-CoTAPc films towards the oxidation of the thiols increases slightly with the thickness of the film, but remains similar to that of the adsorbed monomeric CoTAPc. The higher stability of the electropolymerized poly-CoTAPc films makes them attractive for applications in the activation and/or the detection of thiols. We have assessed this approach by designing ultra-microcarbon-fiber electrodes, coated with poly-CoTAPc, and combining their use with different electrochemical techniques (cyclic voltammetry, differential pulse voltammetry and differential normal pulse amperometry) for the electroanalysis of the examined thiols.